Right Ventricular Involvement in Hypertrophic Cardiomyopathy

The aim of this study was to assess, using cardiovascular magnetic resonance (CMR), whether morphologic right ventricular (RV) abnormalities are present in patients with hypertrophic cardiomyopathy (HC). Left ventricular hypertrophy has been considered the predominant phenotypic expression of HC. Whether structural abnormalities of the right ventricle are also present in HC is unknown. CMR provides complete coverage of both ventricles with high spatial resolution. CMR was applied to study RV morphology in HC. CMR was performed on 46 subjects with HC (mean age 39 ± 16 years; 70% men) free of pulmonary hypertension and 22 healthy subjects (mean age 44 ± 16 years; 50% men). Mass, wall thickness, chamber volume, the ejection fraction, and fibrosis were assessed for both ventricles. Maximum RV wall thickness was increased in patients with HC compared with referent controls (7 ± 2 vs 5 ± 1 mm, p <0.001), including 15 (33%) with maximum wall thicknesses ≥8 mm (≥2 SDs higher than the mean for controls) and 4 (9%) with extreme hypertrophy (≥10 mm). RV hypertrophy was predominantly a diffuse process involving the entire or a significant proportion of the RV wall in most patients (n = 8 [53%]). The RV wall mass index was also increased in patients with HC (28 ± 9 vs 22 ± 4 g, p <0.001). A significant correlation was found between maximum RV and left ventricular wall thickness (R2 = 0.4, p <0.001) and between RV and left ventricular mass (R2 = 0.4, p <0.001). Only 1 (2%) patient with HC had evidence of RV wall fibrosis. In conclusion, morphologic RV abnormalities are present in a substantial proportion of patients with HC.